There have been several attempts to improve the measurement of fiber concentration in a so called refiner zone of a fiber pad distribution being processed between mill plates (discs) of a refiner. New measurement techniques have been developed to keep the quality of the pulp as consistent as possible. Sensor means are mounted in refiners for measure of fiber concentration in the fiber pad. Paper making industry using refiners has interest in saving energy and there is a desire to balance energy consumption and fiber material refining process using such sensor means. However, there are still no efficient way to measure fiber concentration and steam point between refiner plates for reaching a high quality production at the same time energy saving process. In research work so called sensor-rich systems are used for estimation of fiber consistency. However, such systems are bulky and require complex software applications executing data from temperature sensors, motor loads, dilution water feeding rate, inlet temperature and pressure, material properties etc. The use of temperature data is hazardous since the temperature per se does not indicate the refiner pad consistency and fiber concentration.
The applicant of this application also presented one way to overcome above problems according to an alternative solution in the document WO 2005/083408. It reveals that the magnitude of the movement of an impedance sensor body and the change of the impedance over said movement can be used for determination of a value for a dielectric constant of the refiner pad. Software is used for determination of the fiber concentration. A correlation between dielectric constant and degree of fiber concentration is utilized for determination of the fiber concentration. The device disclosed in WO 2005/083408 is of high technical value to the field. However, there is a desire to develop and simplify known devices for determination of the fiber concentration of a refiner pad within the refiner zone and for determination of the steam point of the refiner in-between the plates.
It is desirable save further energy in the paper making industry.
It is desirable to produce a high quality pulp by proper measurement of fiber concentration in the refiner pad.
It is desirable to detect in which region of the refiner plate gap the steam point prevails.
The invention is provided for solving a problem defined by the enclosed independent claims and related to the technical field.